The Effect of Venovenous Extracorporeal Lung Assist on the Oxygenation of Mixed Venous Blood : Comparison of venovenous bypass using a dulble lumen tube with that using two catheters

Lee, Kook Hyun; Kim, Kwang Woo; Terasaki, Hidenori; Morioka, Tohru

Abstract

At the beginning of 1980's, respiratory support by extracorporeal circulation using a membrane oxygenator attracted medical attention again because it could provide the diseased lung with rest. The extracorporeal respiratory support has been called extracorporeal membrane oxygenation (ECMO), extracorporeal CO2, removal (ECCO2R) or extracorporeal lung assist (ECLA). They are the terms used to describe prolonged extracorporeal venoarterial (VA) or venovenous (VV) bypass via extrathoracic cannulation in patients with acute, reversible cardiac or respiratory failure refractory to conventional medical or pharmacologic management. Usually VV bypass is maintained by cannulating the superior vena cava through one major catheter and the inferior vena cava through another. To reduce the number of veins to be cannulated during VV bypass, a double lumen tube was designed. To compare VV ECLA using a double lumen tube with that using two catheters, we observed the changes of the PvO2 (delta PvO2) as a parameter of extracor-poreal oxygenation. A process from ECLA off to ECLA on was performed thirty-three times on 7 mongrel dogs by VV ECLA using a double lumen tube (double lumen group, 16.7+/-1.9 kg, mean+/-standard deviation) and thirty-four times on 6 mongrel dogs by that using two catheters (two-way bypass, control group, 16.1+/-3.0 kg). In double lumen group, bypass flow rate was 52.3+/-15.1ml/kg/min and bypass ratio (bypass flow/cardiac outputX100) was 65.0+/-25.3%. During ECLA off, PvO2, was 43.3+/-6.7 torr and it was raised to 70.1+/-15.4 torr during ECLA on (p<0.001). delta PvO2 was 27.2+/-17.8 torr. In control group, bypass flow rate was 56.1+/-20.5 ml/kg/min and bypass ratio was 72.3+/-29%. During ECLA off, PvO2, was 39.4+/-7.8 torr and it was raised to 58.4+/-3.9 torr during ECLA on (P<0.001). delta PvO2 was 18.3+/-7.9 torr. delta PvO2, of double lumen group was higher than that of control group (p<0.001). The rise of delta PvO2, (y) following the increaae of bypass ratio (x) was y= -6.54+0.50x (r=0.71, P< 0.001) in double lumen group, and y=0.67+0.26x (r=0.88, P<0.001) in control group. It could be concluded that the rise of PvO2 was obtained more efficiently in double lumen group than in eontrol group (p<0.001). A double lumen tube may permit the simplicity of an operation and patient care as well as minimizing the bleeding during clinical ECLA.